Bradycardia-hypotension syndrome in acute myocardial infarction. Reappraisal of the overdrive effects of atropine.

Sixty-eight (17 per cent) of 380 patients with acute myocardial infarction had the bradycardia-hypotension syndrome (ventricular rate below 60/min and systolic blood pressure less than 100 mm Hg) during the first 24 hours of admission to a large general hospital. In 61 of the 68 patients, the administration of atropine significantly increased the heart rate (from 46 plus or minus 14 to 79 plus or minus 12/min) (p less than 0.01) and systolic blood pressure (from 70 plus or minus 15 to 105 plus or minus 13 mm Hg) (p less than 0.001). In 26 of the 68 patients, ventricular premature complexes decreased from 9.4 plus or minus 3/min to 2.4 plus or minus 0.7/min (p less than 0.001) after the administration of atropine. It is concluded that the bradycardia-hypotension syndrome is not an uncommon complication following acute myocardial infarction and that selected doses of atropine may have a beneficial effect without significant complications.